In a large Dutch oven, brown the hot Italian sausage, breaking it into small crumbles. Cook it all the way through before moving on. If using pork sausage, it should reach 160°F.
Add the diced red onion and green bell pepper to the browned sausage. Stir and cook until the vegetables have softened.
Stir in a big scoop of minced garlic and cook for about 1 minute.
Squeeze in the tomato paste. Stir it through the sausage and vegetables and let it cook for a few minutes, until the paste develops a deeper color.
Add the dry orzo to the pot. Stir to coat it with the sausage and tomato mixture, letting it toast briefly and pick up that flavor.
Pour in the chicken stock or broth and the tomato sauce. Fill the empty 8-oz tomato sauce can with heavy cream and add that, too. Sprinkle in crushed red pepper flakes and Italian seasoning, then stir everything together.
When the mixture starts bubbling, turn the heat down to a gentle simmer. Cover and cook for about 12 to 15 minutes, until the orzo is tender. Stir often and check the liquid level. Add a splash of water if the mixture gets too thick before the pasta is done.
Once the orzo is tender, turn off the heat. Add the block of Boursin Garlic & Fine Herbs cheese, break it apart, and stir until it melts completely into the pasta and the sauce is smooth and creamy.
Spoon it into bowls and serve warm.